[llvm] 3f0e670 - [Attributor][NFCI] Expose some nosync reasoning to outside users.

[Johannes Doerfert via llvm-commits]

Author: Johannes Doerfert
Date: 2022-02-01T01:07:50-06:00
New Revision: 3f0e670498cb923a7f8e8f779db660770e05ebc0

URL: https://github.com/llvm/llvm-project/commit/3f0e670498cb923a7f8e8f779db660770e05ebc0
DIFF: https://github.com/llvm/llvm-project/commit/3f0e670498cb923a7f8e8f779db660770e05ebc0.diff

LOG: [Attributor][NFCI] Expose some nosync reasoning to outside users.

No-sync is a property that we need in more places as complex
transformations emerge. To simplify the query we provide an
`AA::isNoSyncInst` helper now and expose two existing helpers through
the `AANoSync` class.

Added: 
    

Modified: 
    llvm/include/llvm/Transforms/IPO/Attributor.h
    llvm/lib/Transforms/IPO/Attributor.cpp
    llvm/lib/Transforms/IPO/AttributorAttributes.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Transforms/IPO/Attributor.h b/llvm/include/llvm/Transforms/IPO/Attributor.h
index 254a2f36bd7c6..20521adfa3e72 100644
--- a/llvm/include/llvm/Transforms/IPO/Attributor.h
+++ b/llvm/include/llvm/Transforms/IPO/Attributor.h
@@ -139,6 +139,11 @@ class Function;
 /// Abstract Attribute helper functions.
 namespace AA {
 
+/// Return true if \p I is a `nosync` instruction. Use generic reasoning and
+/// potentially the corresponding AANoSync.
+bool isNoSyncInst(Attributor &A, const Instruction &I,
+                  const AbstractAttribute &QueryingAA);
+
 /// Return true if \p V is dynamically unique, that is, there are no two
 /// "instances" of \p V at runtime with 
diff erent values.
 bool isDynamicallyUnique(Attributor &A, const AbstractAttribute &QueryingAA,
@@ -2989,6 +2994,14 @@ struct AANoSync
   /// Returns true if "nosync" is known.
   bool isKnownNoSync() const { return getKnown(); }
 
+  /// Helper function used to determine whether an instruction is non-relaxed
+  /// atomic. In other words, if an atomic instruction does not have unordered
+  /// or monotonic ordering
+  static bool isNonRelaxedAtomic(const Instruction *I);
+
+  /// Helper function specific for intrinsics which are potentially volatile.
+  static bool isNoSyncIntrinsic(const Instruction *I);
+
   /// Create an abstract attribute view for the position \p IRP.
   static AANoSync &createForPosition(const IRPosition &IRP, Attributor &A);
 

diff  --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index 3f2970dc643d2..d4e386763d42e 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -183,6 +183,31 @@ ChangeStatus &llvm::operator&=(ChangeStatus &L, ChangeStatus R) {
 }
 ///}
 
+bool AA::isNoSyncInst(Attributor &A, const Instruction &I,
+                      const AbstractAttribute &QueryingAA) {
+  // We are looking for volatile instructions or non-relaxed atomics.
+  if (const auto *CB = dyn_cast<CallBase>(&I)) {
+    if (CB->hasFnAttr(Attribute::NoSync))
+      return true;
+
+    // Non-convergent and readnone imply nosync.
+    if (!CB->isConvergent() && !CB->mayReadOrWriteMemory())
+      return true;
+
+    if (AANoSync::isNoSyncIntrinsic(&I))
+      return true;
+
+    const auto &NoSyncAA = A.getAAFor<AANoSync>(
+        QueryingAA, IRPosition::callsite_function(*CB), DepClassTy::OPTIONAL);
+    return NoSyncAA.isAssumedNoSync();
+  }
+
+  if (!I.mayReadOrWriteMemory())
+    return true;
+
+  return !I.isVolatile() && !AANoSync::isNonRelaxedAtomic(&I);
+}
+
 bool AA::isDynamicallyUnique(Attributor &A, const AbstractAttribute &QueryingAA,
                              const Value &V) {
   if (auto *C = dyn_cast<Constant>(&V))

diff  --git a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
index ea3f449b649a8..4eced5dd18e88 100644
--- a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -1766,24 +1766,16 @@ struct AANoSyncImpl : AANoSync {
 
   /// See AbstractAttribute::updateImpl(...).
   ChangeStatus updateImpl(Attributor &A) override;
-
-  /// Helper function used to determine whether an instruction is non-relaxed
-  /// atomic. In other words, if an atomic instruction does not have unordered
-  /// or monotonic ordering
-  static bool isNonRelaxedAtomic(Instruction *I);
-
-  /// Helper function specific for intrinsics which are potentially volatile
-  static bool isNoSyncIntrinsic(Instruction *I);
 };
 
-bool AANoSyncImpl::isNonRelaxedAtomic(Instruction *I) {
+bool AANoSync::isNonRelaxedAtomic(const Instruction *I) {
   if (!I->isAtomic())
     return false;
 
   if (auto *FI = dyn_cast<FenceInst>(I))
     // All legal orderings for fence are stronger than monotonic.
     return FI->getSyncScopeID() != SyncScope::SingleThread;
-  else if (auto *AI = dyn_cast<AtomicCmpXchgInst>(I)) {
+  if (auto *AI = dyn_cast<AtomicCmpXchgInst>(I)) {
     // Unordered is not a legal ordering for cmpxchg.
     return (AI->getSuccessOrdering() != AtomicOrdering::Monotonic ||
             AI->getFailureOrdering() != AtomicOrdering::Monotonic);
@@ -1812,7 +1804,7 @@ bool AANoSyncImpl::isNonRelaxedAtomic(Instruction *I) {
 /// Return true if this intrinsic is nosync.  This is only used for intrinsics
 /// which would be nosync except that they have a volatile flag.  All other
 /// intrinsics are simply annotated with the nosync attribute in Intrinsics.td.
-bool AANoSyncImpl::isNoSyncIntrinsic(Instruction *I) {
+bool AANoSync::isNoSyncIntrinsic(const Instruction *I) {
   if (auto *MI = dyn_cast<MemIntrinsic>(I))
     return !MI->isVolatile();
   return false;
@@ -1821,24 +1813,7 @@ bool AANoSyncImpl::isNoSyncIntrinsic(Instruction *I) {
 ChangeStatus AANoSyncImpl::updateImpl(Attributor &A) {
 
   auto CheckRWInstForNoSync = [&](Instruction &I) {
-    /// We are looking for volatile instructions or Non-Relaxed atomics.
-
-    if (const auto *CB = dyn_cast<CallBase>(&I)) {
-      if (CB->hasFnAttr(Attribute::NoSync))
-        return true;
-
-      if (isNoSyncIntrinsic(&I))
-        return true;
-
-      const auto &NoSyncAA = A.getAAFor<AANoSync>(
-          *this, IRPosition::callsite_function(*CB), DepClassTy::REQUIRED);
-      return NoSyncAA.isAssumedNoSync();
-    }
-
-    if (!I.isVolatile() && !isNonRelaxedAtomic(&I))
-      return true;
-
-    return false;
+    return AA::isNoSyncInst(A, I, *this);
   };
 
   auto CheckForNoSync = [&](Instruction &I) {